A dolly stabilizer is mounted onto a rear end of a trailer and has a stabilizer plate, a stabilizer pin, and a control box. The stabilizer plate is mounted to a chassis having at least one pair wheels. The stabilizer plate may comprise a plurality of mounting holes. It includes a dolly tongue stabilizer pin hole that receives the stabilizer pin. The stabilizer plate includes an internal piston that is selectively driven into a recess or opening in the stabilizer pin to straighten a position of a subsequent trailer or dolly relative to a preceding one. The control box includes a pneumatic input for receiving pressurized air and a pneumatic output to brakes on the dolly. A speed sensor may be coupled to the control box for allowing speed control of the dolly wheels. Electrical connections accept power for operating lights and other electrical devices on the dolly.